Pneumatic lifting jack



Dec. 19, 1922. 1,439,105..

1. c. HILL: PNEUMATIC LIFTING JACK.

FILED AUGJI. I921- Patented Dec. 19, 1922.

JOHN C. HILL, OF CHICAGO, ILLINOIS.

PNEUMATIC LIFTING JACK.

Application filed August 11, 1921.

To all whom it may concern:

Be it known that 1, JOHN C. HILL, a citi- Zen of the United States bf America, and a resident of Chicago, in the county of Cook, State of Illinois, have invented certain Improvements in Pneumatic Lifting Jacks, of which the following is a specification.

This invention relates to pneumatically or fluid actuated lifting jacks and has for its object:

'To provide an effective and substantial locking means for securing the movable member of the jack in its-raised position, and with which a ready release can be attained by the operator, all as will hereinafter more fully appear.

In the accompanying drawing:

Fig. 1, is a central vertical section of a lifting jack embodying the preferred form of the invention.

Fig. 2, is an elevation of the same.

Fig. '3, i s a sectional plan on line 33, Fi 1.

fiike reference numerals indicate like parts in the different views.

Referring to the drawing, 1 designates the cylinder of the jack closed at its lower end by a fixed head 2, and at its upper end by a removable head 3 which forms a guide for the stem or rod of the movable piston of the jack. To such end said head is provided With a central guide head or block 4, as shown.

5 designates the pressure inletoutlet neck of the cylinder 1, the passage of which extends to the lower end of said cylinder as shown, and in cases where air pressure is used to operate the ack the neck 5 is pro vided with a valved nipple 6, preferably of the type used in pneumatic tire inflation.

7 designates the movable piston of the jack of any usual construction, fitting the bore of the cylinder 1 and provided with a stem or rod 8 which extends up through the guide head 4 aforesaid and carries at its upperend the usual work engaging saddle or head 9. I

10 designates counter art semi-rotary holding heads of'a circu ar form in cross section, turning in parallel bores, formed therefor in the guide head 4-aforesaid at opposite sides of the passage in said head for the piston rod 8.

11 designates gear wheels secured at one end of the semi-rotary heads 10, meshing one with the other, and adapted to im- Serial No. 491,346.

tendency to move the semi-rotary heads 10 into locking engagement with the piston rod above referred to.

A material part of the present inventionconsists in the formation of each semi-rotary head 10 aforesaid, with a recess 13 at one side of the periphery with the face of said recess of a flat or straight 'form and adapted for sliding contact with the adjacent face of the piston rod 8 and so that the semi-rotary head is positively held from a turning movement during the main travel of the movable piston and its rod, and until one or more points. are reached in such travel has been reached and in which it is desired to lock the piston rod in a positive and substantial manner against downward movement under the stress of an imposed load. To such end a co-acting formation of the piston rod as follows is provided.

14 designates segmental recesses formed in opposite sides of the piston rod 8 adjacent to the lower end of the same, so that as the piston moves upward and brings the recesses 13 in line with the semi-rotary heads 10, the circular perimeter of said heads are free to turn into the recesses 13 and effect a positive holding of the piston rod against downward movement until such holding-or locking engagement is released. Such release is attained by manual turning of the heads 10 in a reverse direction by means of the hand lever 12 to bring the flat or straight faces of the aforesaid recesses 13 into parallel relation to the respective sides of the piston rod.

In practice one pair of recesses 14 will serve all usual purposes, when however a locking of the piston rod at different heights is required, such purpose can be obtained by two or more pairs of the recesses 14 formed at spaced relation in the piston rod. It is also within the scope of the present invention to use a single semi-rotary head 10 in effecting the described locking of the piston rod against downward movement, when a simpler and less expensive structure is desired.

Having thus fully described my invention what I claim as new and desire to secure by Letters ?atent, is

1. In a lifting jack or the like,.the com bination of a movable member a stationary member having a guide head for said movable member, a pair of semi-rotary heads journalled in said guide head and formed with flat faces adapted for bearing contact with side faces of the movable member, the movable member having segmental recesses in said opposite side faces adapted toregister with said semi-rotary heads and permit the same to turn into locking engagement with said segmental recesses, means for imposing simultaneous movement on said semi-rotary heads, and manual means for effecting a releasing movement of the semi-rotary heads in the reverse direction.

2. In a lifting jack or the like, the combination of a movable member, a stationary member having a guide head for said movable member, a pair of semi-rotary heads journalled in said guide head and formed with flat faces adapted for bearing contact with opposite side faces of the movable member, the movable niember having segmental recesses in said opposite side faces adapted to register with said semi-rotary heads and permit the same to turn into locking engagement With said segmental recesses, means for imposing simultaneous movement on said semi-rotary heads, and manual means for effecting a releasing movement of the semi-rotary heads in the reversedirection, the same comprising a gravity lever attached to an end of one of said semi-rotary heads.

3. In a lifting jack or the like, the combination of a movable member, a stationary member having a guide head for said movable 'member, a pair of semi-rotary heads journalled in said guide head and formed with flat faces adapted for bearing contact with opposite side faces of'the mov able member, the movable member having segmental recesses insaid opposite side faces adapted to register with said semi-rotary heads and permit the same to turn into look ing engagement with said segmental recesses, sector gears on said semi-rotary heads adapted to impose simultaneous movement on said heads, and manual means for effecting a releasing movement of the semi-rotary heads in the reverse direction.

4. In a lifting jack or the like, the combination of a movable member, a stationary member having a guide head for said movable member, a pair of semi-rotary heads journalled in said guide head and formed with fiat faces adapted for bearing contact Withopposite side faces of the movable member, the movable member having segmental recesses in said opposite side faces adapted to register with said semi-rotary,

heads and permit the same to turn into looking engagement with said segmental recesses, sector gears on said semi-rotary heads adapted to impose simultaneous movement on said heads,.and manual means for effecting a releasing movement of the semi-rotary heads in the reverse direction, the same comprising a gravity lever attached to an end of one of said semi-rotary heads.

Signed at Chicago, Illinois, this 9th day of August, 1921. v

' JOHN C. HILL. 

